The problem of coupling of a hole saw to an arbor has been the subject of many patent publications. In industrial and professional applications, sets of differently sized hole saws are used. The hole saws are often cup-shaped with a generally cylindrical skirt connected or co-formed on or with a support portion or carrier plate and saw teeth on a free end. An arbor connects the hole saw to a driving machine, like a drill. Currently, the centre of the carrier plate is provided with an internal screw thread or screw-threaded hole. The arbor has an external screw thread matching the internal thread of the hole. In this way, many types and sizes of hole saws can be fitted onto an arbor.
It was found that in use, the hole saw tends to get locked onto the arbor, making it almost impossible to remove the hole saw from the arbor. To that end, one or more driving pins are provided on the arbor to prevent this (too) tight locking. This, however, requires more complex constructions of the arbor. Several designs are explained in the following patent publications.
U.S. Pat. No. 3,880,546 according to its abstract describes a hole saw assembly including an arbor which comprises a stem, a body, a pilot drill carried by the body, and spring-loaded connecting means adapted to engage appropriate complemental locking means in the base of the cup-shaped hole saw. The hole saw has appropriate arcuate apertures in its base and appropriate inclined ramps which will, upon insertion and twisting movement of the arbor relatively of the saw, permit the spring-loaded locking means to be engaged by the ramps and snapped into place so as to secure the saw to the arbor in secure flush position. A modified form of the invention is also disclosed in which the spring-loaded locking means include fixed T-shaped studs or pins and ball detent means which also engage the base of the saw.
GB2257381 according to its abstract describes an arbor for a hole saw that includes a spindle with a screwthreaded end length for threaded engagement in a screwthreaded hole in a carrier plate part of the hole saw. So that the hole saw does not become tightly locked in position on the arbor, means provided for drivably connecting the hole saw to said spindle include at least one drive pin extending through a clearance hole in a fixed collar and engaging a hole in the carrier plate part of the hole saw. The drive pin is carried by a collar which is slidably mounted on a portion of the spindle, said collar being acted on by a coil compression spring reacting against a washer backed by a circlip.
Many alternatives provide an adapter that is attached to a hole saw and that provides an end of a quick coupling to the arbor. The arbor in turn has a quick-coupling provision that cooperates with the (complementary) quick coupling provision on the adapter. Examples of these solutions are illustrated in the following publications.
DE202013006690U1 according to its abstract describes a holder for coupling a hole saw with a mechanical drive comprising a holding shank for connection to the machine drive, characterized in that the receptacle has a tool-free with the holding shank connectable, the hole saw stationary associated connecting piece.
US20090279972 according to its abstract describes an arbor for quick change and standard hole cutters, wherein each hole cutter includes a central aperture and at least one drive pin aperture. The arbor comprises an arbor body including an end portion engageable within the central aperture, a drive shank opposite the end portion for engaging a power tool, and an aperture for receiving a pilot bit. The arbor further comprises a drive pin plate and/or collar having at least one drive pin receivable in a corresponding drive pin aperture of the hole saw for drivingly engaging the hole saw. The arbor, in at least one embodiment, further comprises a pilot bit mechanism for engaging and releasing a quick change or standard pilot bit.
US20110255931 according to its abstract describes a hole saw arbor system includes a tool-bit holder comprising a body having a proximal end and a distal end, the proximal end configured to be coupled to and driven by a driving device. A substantially longitudinal tool-bit holder bore may extend from the proximal end to the distal end of the body, the bore configured to receive a drill bit. The system further includes an arbor configured to be releasably coupled to a portion of the drill bit. The arbor may include a body having a proximal end and a distal end, the proximal end configured to matingly engage the distal end of the tool-bit holder when the arbor is coupled to the drill bit. The distal end may be configured to be coupled to a hole saw. A substantially longitudinal arbor bore may extend from the proximal end to the distal end of the body, the arbor bore being configured to receive the drill bit. The arbor may further include a locking mechanism positioned within a portion of the body, the locking mechanism configured to releasably couple the arbor to at least a portion of the drill bit when the drill bit is within the arbor bore.
WO2001038028 according to its abstract describes a hole saw assembly that provides a structure and method for efficiently and securely connecting a hole saw to an arbor and easily connecting a pilot bit to the arbor. The arbor has a shank opposite a coupling end and a receiving slot proximate to the coupling end. The receiving slot is adapted to receive a mounting tag of the hole saw to couple the hole saw to the adapter body. The arbor also includes a selector sleeve slidably coupled to the body for movement between a first position allowing the receiving slot to receive the hole saw and a neutral position wherein the selector sleeve prevents removal of the hole saw mounting tab from the receiving slot.
WO2006062388 according to its abstract describes a quick-change arbor for a tool, in particular a hole saw, the arbor comprising a longitudinal body having a drive end and a tool end, means for attaching the tool which are provided with a central hole allowing a sliding of the attachment means over the longitudinal body, and means for rotationally and axially locking the attachment means to the longitudinal body. The attachment means are slidably releasable from the longitudinal body, and can after applying a latch in the attachment means simply be slid over the body in order to push a plug of the sawn material out of the hole saw.
WO2006122417 according to its abstract describes a quick connect mechanism for mounting a hole saw to a tool comprising a hole saw; a mandrel having a first end for mounting to the hole saw and a second end for mounting to the tool; and a drill bit, assembled within the mandrel such that when the mandrel is connected to the hole saw, the drill bit being concentrically centred within the hole saw; a holder, mounted to the tool, for receiving the second end of the mandrel; wherein the second end of the mandrel includes quick connect means for easily mounting the mandrel to and releasing the mandrel from the holder.
Many adapters are complex, remain on the hole saw, require complex coupling actions from a user, or have other disadvantages. Thus, coupling a hole saw to a driving apparatus provides a problem.